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Merrifield on the Deviation of the Compass

Subjects

Abstract

As a review of my little manual on “Deviation,” &c., has appeared in NATURE for October 17th, in which I am accused of having “written with looseness and inaccuracy,” perhaps you will kindly allow me a small space to answer my critic. He has selected a most unfortunate example to bear out his assertion; and I contend for the accuracy of my statement. “Vertical iron, at the same place, will produce the same deviation in whatever direction the ship's head may be.” Here I do not pretend to say (as my reviewer insinuates), that the whole deviation is the same in every position of the ship's head; but I maintain that that part due to vertical iron remains constant for the same place until a change of secular variation becomes cognisable. I am at a loss to discover either looseness, inaccuracy, or substitution of cause for effect in what follows, and I am inclined to think, if any exists, it must be on the part of my reviewer